Most sudoku apps want something from you — your attention between grids, a streak you have to feed, a video to watch for one more puzzle. Quadretto wants none of it. You open it, you play, you close it. That is the whole product.

• 111,028grids in the app
• 14solving techniques
• $4.99once, everything included

The solver never guesses

A grid only enters the bank if logic alone finishes it. Fourteen techniques, from the last free cell up to XYZ-wing and turbot chains, sorted into five levels by the hardest technique a grid actually needs. If you are stuck, there is a way through — you have not been handed a puzzle that requires trial and error.

A hint tells you where to look before it tells you what to do

Three steps: the region worth looking at, the technique that applies there, then the move. You can stop after the first one. A hint that plays for you teaches nothing.

Free means playable, not crippled

The daily challenge and one free game every day, with every technique, every hint and the full guide included. Pro removes the daily limit. The purchase screen appears when you start a game past the limit, never in the middle of a grid.

Nothing to keep up with

No streak, no reminder notification, no badge counting up on the icon. Come back in three weeks and nothing has been lost, because there was nothing to lose.

On the Home Screen and the Lock Screen

A widget shows the day's challenge. It works out the calendar itself rather than carrying the engine around, and a test checks it still agrees with the app.

It asks for no permissions at all

No camera, no microphone, no location, no contacts, no notifications — the app declares not a single permission. iCloud syncs your progress through your own account. There is no analytics, no third-party code, and nothing that reaches the network. The privacy page is the shortest of the nine for that reason.

Seven languages, nine variants: English, French, German, Spanish (Spain and Latin America), Italian, Japanese and Portuguese (Brazil and Portugal). iPhone in portrait; iPad in all four orientations, grid and keypad side by side in landscape.

Quadretto is at version 0.1 and has not been built yet. There is nothing to download — this page will carry the link when there is.